Nose tackles bring to mind down-and-dirty defensive linemen intensely fighting off blockers in the trenches -- including double- and triple-teams -- in their job to plug up the middle and stop the run.

Army's football coaches believe they have such a run-stuffer for the future when Ammon Tuimaunei arrives at West Point in 2013 after a year at the USMAPS (prep school).

The 6-foot-2, 270 pound Tuimaunei is looking forward to playing the role and is heavily into a new training regime to prepare for the next level as he finishes up his senior year at Wilsonville (Ore.) High. But these days Tuimaunei portrays quite a contrast to a down-and-dirty defensive lineman to the hikers and nature lovers he encounters as he serenely pedals his mountain bike over hillside trails 20 miles south of Portland.

Tuimaunei said his mountain bike "is pretty suped up" to support his weight, but he feels he's found an effective method to take off bad weight (baby fat) and put on good weight (muscle). It's a step essential to the evolution for all big high school kids who relied on his size if they hope to develop into a Division I college athlete who can compete against other big guys.

"I like the weight training packet (Army) gave me," Tuimaunei said. "It's a 50 pages. It's not just about weight lifting. It's also about nutrition and drills. I'm losing weight and replacing it with muscle."

Tuimaunei says he may not develop into a 300-pounder that are common among college football nose tackles these days, but he's confident he can play at 290 pounds. That would represent a 30-pound upgrade from last year's starting nose tackle as Army coach Rich Ellerson and his staff strive to bulk up their defensive line.

But not weighing 300 pounds doesn't concern Tuimaunei. The Black Knights' defense is designed to compensate for a lack of size with quickness and strength and that was a factor that attracted him to casting his future with Army.

"My offers dropped off when I got hurt," said Tuimaunei, referring to a broken foot his senior year. "But I think I would have signed with West Point anyway. When Army recruited me, I liked how they talked about how it's not how big you are -- it's about strength and speed. I think I'm pretty fast for my size. I think I'm a good match for Army's defense."

Tuimaunei also has a cousin he can turn to for advice to succeed at the college level. Suaesi Tuimaunei played at Oregon State and spent the 2011 season as a safety on the Atlanta Falcons' practice squad. But Ammon says he already understands the most important element.